Damper device



May 14, 1940. F. D. HOFFMAN DAMPER DEVICE 2 Sheets-Sheetl l Filed June 29, 1938 Patented May 14, 1940l I. 2,200,248 DAMPER DEVICE Fred D. Harman; clevelami, ohio y Application June 29, lass-,iscritti No. 216,498` 4 Claims. (C1. '12e-29:3

y This invention relates toa damper device for use in connection with furnaces and particularly` to .a check damper operatively associated with the furnace exhaust iiue so as to'reduce the flue temperature, tov effect betterfcombustion of the fuel with a consequent reduction of smoke.r

A morespecifcuobject is to providea damper which admits outside air through 'the 'exhaust iluein such a manner thatit retards the discharge of the gases from the re pot and assures more nearly complete combustion thereof prior` to the passage of the gases into the furnace stack and which rcauses a large vpercentage of the air so admitted to pass beyond lthe rstack and enter the fire pot of the furnace to assist in sustaining combustion of the gases evolved therein.

Another specific object is to deflect the airso adrriittedin a manner to produce a swirling motion `of the resultant air streamfiowing into'l the mi? Pot-'i I Other objects and advantages willbecome apparent-from the following specicationwherein reference'is made to the drawings, inwhich:

14 is aside elevation of adomestic hotair.

furnace with the device of the present invention installed thereon;

2lis an enlarged outer end elevation ofthe damper device of the present invention as viewed from'the right in Fig.,1; f "f y FigLB is a sectional view of the 'damper device anda part of the exhaust ue and is taken on a plane indicated by the line 3--3 in Fig. 2;

4 is an elevation, partly Ainy section, of 'the adjustable element of the' damper device viewed from the inside'of the furnace flue, as .indicated by the line 4--4 in Fig. 3; and

Figs. 5, 6 and '7 are fragmentary sectional views taken on lplanes indicated by the lines and 'I--1`, respectively, in Fig. 4.

AReferring to the drawings, the furnace com? prises a vfire pot I spanned at vthe bottom by the usual grate bars (not shown) and having therebeneathv the usual ash pit into which air is ad#r mittjed through a damper 2 for sustaining com.

bustion. Surr'nounting the fire pot IA is the cus-- tomary large radiating head or radiator 3 which is connected to the usual horizontally extending exhaust flue 4, the flue in turnbein'g connected to' an'iupwardly extending stack- 5. The exhaust vflue 4 has afportion providing an extension t which extends beyond the stack 5, the extension 6 being* open at its outerv end. The damper device of the present invention, designated generally at I0, is installed on the outer end of the extended portion of the exhaust flue, and, as better illusplate I3.

open end ,ofy the flue, as illustrated, but is pro' Hrs-i1 trated ink Figs. Zand 3, comprises a cast iron annularheader orcollar I I which vis snugly fitted ontofthe. endue extension 6. Hingedly connected by a suitable pin I2 to suitable lugs-on the upperr edge of the header II is the damper cover` The coverplate I3 normally closes ther vided with a plurality of openings I4 in the form `of circular sectors uniformly distributed about' thecenterof the plate I3. The plate I3`is prov idedwith af central 'hub` I5 which is received ais'uitable'shaft I5 which extends coaxially of the plate I3. The ,shaft I6 has a threadedportion engaging internal threads in the hub I5 so that it may be adjusted axial1y,a locking` nut 'I being'provided for locking krthe shaft in the desiredadjusted position. Rotatably mounted on a plurality of openings I9 corresponding infsize and shape to andarranged for registry with the openingsM of the damper plate I3. The damper Ifis rotatable. about the shaft` I5 and, for 'illustration only, the rotation maybe effectedby a bi-metal thermostatic coilr 20, one end of whichy is secured to theshaft I6 ,by a suitable screw 2lk andthe other end ofwhich is secured to a hub portion 22 on thedamper I8. The thermostatic coil 2!) can' be so `arranged that when unheated,

itA rotates the damper I 8 to av positionwhereinthe openings I9 are rout of registry with theopeiiil in'gs I4 and-"the admission of air is. substantially stopped. When the coil 20 is heated, it rotates' thejdamper plate to bring the vopenings I9r gradually into registry with the openings I4 for ad'- niitting air, variations in the'amount of air ,ad :3.

mitted being effected between 'the' extreme positions. 'Suitable stops are provided on the damper I8 and engage a suitable stop-ping lug 24 on the plate I 3' lfor limiting the movement 'of the rotatf able damper I8 from a position in which the openings I4 are entirely blocked to a position in whichthey are ink full registry with the openinjgsm.`

fNo claim is made herein to the thermostatic adjustment above described' of the vice I8, etc., as shown in Fig. 3.

Asillustrated, the axis vof the shaft lslopes downwardly toward the re pot so that air entering through the registering y part ofthe openings I Il and Il) tends to flowvdownwardly throughthe extension G and flue 4.' With' the structure thus far: described, the air vadmitted would tend'to flow downwardly into the flue extension and toward the radiating hood 3. of the furnace, but

. due to the upward pull of the stack 5, and pardamper de- 'the shaft I6 is a rotatable damper I8 whichA has l tial heating of the admitted air, this air would soon lose its inward velocity and movement tofv Ward the radiating hood 3 and rise and partially return and flow out through the stack 5 so that substantially none of the air admitted would reach the furnace.

It is desirable, however, to admit air entirely into the furnace through the exhaust flue while the re is in check in order to sustain combustion of the fuel and evolve the gases while `the damper 2 is fully or partially closed. Further, it is desirable to retard the escape of unburned gases through the stack 5. In order to insure the passage of the air entirely into the radiating hood 3 of the furnace, a plurality of baffle vanes 25 are provided on the rotatable damper I8 in alignment with the openings I9.

As better illustrated in Figs. 5 to '7, inclusive,

each baille vane 25 is substantially coextensive with and aligned with the projected area of the associated opening I9. Likewise, each baillej25 is concave toward the associated opening I9 land beginning at the plane of the outer face of the damper I 8 at one edge of its opening I 9, slopes inwardly on a` gradual curve and terminates substantially in alignment with the opposite edge of its opening I9 a short distance behind the plane of the outer faceof the plate IB. The wall of the balile at its discharge edge, indicated at 26, is substantially parallel to the plane of the outer face of the damper I8. The curve and length of the baffle in the direction of flow of air therealong is decrescent from the periphery of the damper I8 toward the axis thereof. Furthermore, each baffle 25 has a peripheral wall 21 so that all air entering any one'of the passages I9 is constrained to ow along the baille 25 and be discharged inwardly from the damper I8 as a spiral stream swirlingabout the extended axis of the damper I8. By virtue of the swirling motion imparted to the airadmitted through the damper device' IIJ, the induced air travels a much greater distance longitudinally of the flue and does not tend to reverse and by-pass through the stack 5. On the contrary, it appears that the action is as follows: the stream of air from the baliies 25 is deected downwardly by the outcoming heated products of combustion from the re pot as the products rise and follow along the upper wall portion of the flue 4.. A considerable amount of unburned gases also'tendsv to escape but is relatively unheatedand tends to lie in strata below the hot products. 'I'hese unburned gases become mixed with the admitted air though the hotter products of combustion may escape through the flue. This compression of the area of the swirling stream of air by the escaping products does not appear to retard its flow, and a large amount of such air enters the hood 3 wherein, being somewhat heated, mixesV with the unburned gases which are then ignited and consumed in the hood 3. In order to render the rotation .of the damper I8 easily rotatable,y it may be spaced slightly from the cover plate I 3'by a washer 28. Due tothis spacing, a slight seepage of air past the damper may be permitted at all times. y

On the usual hot air domestic furnace, it has been found that by the use of the present device the flue temperature, which normally reaches about 5 60 degrees F., is maintained at less than 275 degrees F. by the present damper device and that the efciency of the furnace is raised from a normal efciency of 37% to an efliciency of 60.8%. Furthermore, the usual amount of smoke `discharged from the stack is reduced very noticeably and the heat supplied from the furnace is rendered much more uniform and the re maintained for longer periods with a considerable reduction in the amount of fuel supplied and the attendance required for the furnace.

Having thus described my invention, I claim: 1.*A check damper devicefor a vfl'i'rnace hav#- ing a substantially horizontal exhaust iue open at its outer end and connected at its inner end with the furnace and having an upwardly dif rected stack between its ends, saidV damper device comprising a plurality of openings adapted to admit outside air into the open end of said flue, and means respective to said openingsand positioned directly adjacent thereto and inclined relativeto the normal paths of air into said openings in a manner to cause said air to flow as a spiral swirling stream from the open end of,

the flue into the furnace. 2. A check damper device for a furnace having a substantially 'horizontal exhaust flue open at its outer end andan upright stack 'connected to the flue between the open end and the furnace, and comprising a member normally clos-Iv ing the open end ofthe ue andhaving open; ings for admitting outside air into the flue,lanlv adjustable damper cooperable with Vsaid inem-f1. ber for opening and closing said openingstoi control the volume of airadmitted thereintof.4 and means carried by'said damper for deflect#V ing the admitted air as an annular swirling stream directed along the flueltoward the furl-[ nace.

3. A check damper device for a furnace having for deflecting the admitted air as an annular,

swirling stream directed the furnace.

4. A check damper for a` furnace ih avinga substantially horizontal exhaust flue open-at its:

along the fluer r4toward outer end and connected at its other end tothe furnace, and an upright stack connected to the'V 'ue between the open end andthe furnace; and- E comprising a cover plate normally closing the open end of the ue and having a plurality ofopenings therein, a rotatable damper coaxial therewith and having' openings arranged for reg-f istry with and offset relation to the openings ofthe cover plate, baflles on the rotatable damper and aligned with the openings therein,` respecfv tively, said baflles being curved in cross section-i and concave toward the apertures and extending fromv the plane of the damper inwardly-S for deflecting the air entering the'apertures,spirallyf along the ue. Y l FRED D. HOFFMAN.; 

